Telescopic Encryption: Encrypt text using part result to encrypt the rest

This class can encrypt text using part result to encrypt the rest.

It takes a given text string and a key position to encrypt the text by looking up a table gets the encrypted character based on each character that is being encrypted and the current key position.

The key position changes to one that depends on the previous encrypted text characters.

The class can also do the opposite, i.e. decrypt a previously encrypted string inverting the process.